岩石矿物学杂志2025，Vol.44Issue(4)：895-923,29.DOI:10.20086/j.cnki.yskw.2025.4204
秦-祁结合部位陇山杂岩变泥质岩变质作用及年代学研究
Metamorphism and geochronology of metapelites from the Longshan Complex at the Qinling-Qilian junction zone
摘要
Abstract
The Longshan Complex located in the Qinling-Qilian junction zone is the key to understanding the tec-tonic evolution of this junction.This study conducted petrographic observations,phase equilibrium modeling and monazite U-Pb dating,to better discuss the tectonic implication.Based on petrographical observation and mineral composition analysis,the garnet biotite plagioclase gneisses sample 21LS30-1 of the Longshan Complex display two metamorphic mineral assemblages:the prograde stage(M1)(biotite+plagioclase+quartz+rutile+ilmenite)and the peak stage(M2)(biotite+garnet+plagioclase+quartz+rutile+ilmenite+melt).Sample 21LS37 exhibits two sets of metamorphic minerals during different formation stages:the prograde stage(M1)(biotite+sillimanite+plagioclase+quartz)and the peak stage(M2)(biotite+sillimanite+garnet+K-feldspar+plagioclase+quartz+ilmenite+melt).Phase equilibrium modeling constrained the peak p-t conditions of the two samples to be 813～821 ℃,1.08～1.1 GPa and 815～819℃,0.93～0.97 GPa,reaching the medium-pressure granulites facies metamorphism.LA-ICP-MS monazite data from the garnet biotite plagioclase gneisses show 206Pb/238U ages of 451～425 Ma,455～431 Ma,415～395 Ma and 415～394 Ma,respectively.The Longshan Complex and the North Qinling Orogenic Belt underwent similar tectonic processes during the Paleozoic.We preliminarily proposed that the Longshan Com-plex belongs to the western extension of the North Qinling orogenic belt and has experienced Paleozoic continental-continental collisional orogeny.关键词
秦-祁结合部位/陇山杂岩/相平衡模拟/独居石U-Pb定年/陆陆碰撞造山作用Key words
Qinling-Qilian junction zone/Longshan Complex/phase equilibrium modeling/monazite U-Pb ages/continental collisional orogeny分类
天文与地球科学引用本文复制引用
栗娟娟,卢俊生..秦-祁结合部位陇山杂岩变泥质岩变质作用及年代学研究[J].岩石矿物学杂志,2025,44(4):895-923,29.基金项目
国家自然科学基金项目(41872195) （41872195）
科技部大陆动力学国家重点实验室项目 National Natural Science Foundation of China(41872195) （41872195）
Project of the State Key Laboratory of Continental Dynamics at Northwest University under the Ministry of Science and Technology （）
